1. Field of the Invention
The present invention is related to an image forming apparatus such as a copying machine provided with a sorter for utilizing an OHP (Overhead Projector) paper.
2. Description of the Related Art
(1) In an OHP copy mode of an image forming apparatus, for example, in a copying machine utilizing a transparent paper such as OHP paper, the OHP paper is beforehand set in a paper cassette and a manuscript is copied with the OHP paper being supplied.
Then when two or more copies of the manuscript are executed, a sort function is frequently used.
In a conventional copying machine, when the OHP copy mode is set, and the sorting mode is set, the copied OHP paper is discharged on a sort bin through an inner passage of the sorter.
Because the OHP paper is comparably thick and lacks flexibility, and since the inner passage of the sorter has a sharply bending part, the passage is often clogged with paper (paper jam).
(2) Another conventional copying machine has a sorter and can also execute various kinds of copy functions, such as cover copy mode, and page writing mode.
In such conventional copying machine, when the operator copies using the sort mode, the operator instructs the sort mode to the primary part of the copying machine and the sorter by pushing a sort mode key on a console. On the other hand, in another conventional copying machine, for avoiding such troublesome operation, when two or more copies of the manuscript are set by a set key, the sort mode controlling is automatically instructed to the primary part of the copying machine and the sorter without the above-mentioned operator's pushing operation.
However in the latter-mentioned copying machine, as above-mentioned, when two or more copies of the manuscript are set by the set key, the sort mode controlling is automatically instructed to the primary part of the copying machine and the sorter. Therefore when the operator wishes to use a group mode, the operator should newly set the group mode. And when the operator forgets the setting of the group mode, the group mode is not executed and the order of the copied papers becomes contradictory to the operator's will.
(3) Another conventional copying machine is known wherein OHP paper and normal paper are alternately supplied to the primary part of the copying machine, and the normal paper and the OHP paper are discharged with the normal paper being between the copied OHP papers.
Such a conventional copying machine is disclosed, for example, in Japanese Laid-Open Patent Publication No. sho 62-59971.
The conventional copying machine comprises plural trays, an OHP paper supplying means for supplying the OHP paper one by one from a tray having the OHP papers therein, a normal paper supplying means for supplying the normal paper one by one from a tray having the normal papers therein, an image forming stopping means for temporarily stopping the image forming, an OHP mode selecting means for setting a mode of forming a copy image on the OHP paper, and a controlling means for controlling the OHP paper supplying means, the normal paper supplying means and the image forming stopping means, and thereby to alternately discharge the copied OHP paper and the normal paper under an OHP mode.
Since the conventional OHP paper copying machine discharges the normal paper and the OHP paper with the normal paper being between the OHP papers, operation and maintenance of the OHP paper is convenient. Then it is preferable that the size of the OHP paper is the same as that of the normal paper and the discharged direction of the OHP paper is the same as that of the normal paper.
However, the above-mentioned OHP paper copying machine lacks such function for making the size and discharged direction of the OHP paper the same as those of the normal paper. Therefore the OHP paper of A4 size and the normal paper of B4 size happen to be alternately discharged. Further, even when the size is the same, on account of the different discharged direction, the operator has to arrange the direction of the discharged OHP paper and the normal paper afterwards.
(4) Recently over-head projectors have often been used in a lectures. An OHP paper as a manuscript is utilized in the over-head projector.
Such an image forming apparatus is known in, for example, Japanese Laid-Open Patent Publication No. sho 62-141576 wherein the OHP paper and a ground sheet are discharged over one another to the same tray, so that the content of the OHP paper is easily read. That is, the OHP paper and the normal paper as the ground paper are alternately supplied and discharged one by one with the OHP paper being at the top. Thus the copied OHP paper and the non-copied normal paper overlap each other in the discharge tray, or the copied OHP paper and the copied normal paper overlap each other in the discharge tray.
On the other hand, the conventional copying machine has a face discharge mode in which the copied paper is discharged with the copied surface upward, and a rear discharge mode in which the copied paper is discharged with the copied surface downward. When the face discharge mode is used, the normal paper serving as the ground paper is laid on the copied surface of the OHP paper discharged in advance, and thus there is the trouble that the normal paper cannot serve as the ground paper.
When the image on the OHP paper is also copied to the normal paper, the trouble is particularly conspicuous.